Blue Sun −28 °C
Description
Blue Sun® −28 °C optimizes heat transfer and thus improves the system’s performance.
A 100 % organic formula (OAT) that guarantees the best protection for all types of metal and is compatible with the plastics and elastomers commonly found on thermal circuits. It protects aluminum and its alloys against corrosion.
Additives are not consumed during use, so there is no need to replenish them with additional products or to check the levels of residual additives on a regular basis.
Blue Sun® −28 °C is based on propylene glycol, so it is non-toxic and safe to handle.
Packaging formats
Advantages
- Protects the circuit from corrosion; specially formulated for aluminium and its alloys.
- It lowers the freezing point and raises the boiling point.
- Prevents foaming.
- Prevents the build-up of sediment and sludge.
- Non-toxic.
- Biodegradable.
- Silicate-free. Prevents gelation and blockage issues.
- Free from nitrites, nitrates, amines, phosphates, benzoates and borax.
- Free of 2HE due to the health concerns.
- Slightly hazardous to water, according to the German WGK1 law.
Technical data
| Property | Value |
|---|---|
| Appearance | Clear blue liquid |
| Propylene glycol content | 42 % P/P |
| Freezing temperature | −23 °C |
| Protection temperature | −28 °C |
| Burst temperature | −32 °C |
| Boiling point (2 bar) | 123 °C |
| pH (20 °C) | 8 – 9 |
Protection temperature: according to ASTM D 1177, the freezing point is the temperature at which the first ice crystal forms. DIN 51583 defines the temperature at which the product ceases to flow and the integrity of the circuit is at risk. Between these two temperatures, there is a mixture of ice crystals and unfrozen fluid that flows without increasing in volume—and therefore without the risk of bursting.
Approvals / Specifications
- AA-52624A · Antifreeze, multi-engine
- ASTM D 3306 · Glycol-based antifreeze for passenger cars and light-duty vehicles
The ASTM D 3306 specification includes the following tests:
| Standard | Test |
|---|---|
| ASTM D 5931 | Relative density |
| ASTM D 1177 | 50 % freezing point |
| ASTM D 1120 | Boiling point of the pure product and at 50 % concentration |
| ASTM D 1119 | Ash content |
| ASTM D 1287 | pH of 50 % dilution |
| ASTM D 3634 | Chloride content |
| ASTM D 1123 | Alkali reserve |
| ASTM D 1882 | Effect on organic finishes |
| ASTM D 1881 | Foaminess |
| ASTM D 1384 | Corrosion in glass container, 33 % dilution |
| ASTM D 4340 | Corrosion of cast aluminum alloys, 25 % dilution |
Certifications issued by INTA (National Institute for Aerospace Technology) laboratories—under the Spanish Ministry of Defence—under document reference CL/RPT/7430/006/INTA/10, covering the concentrated product and its dilutions with water.
Corrosion protection
Mixtures of propylene glycol and water are more corrosive than water. Therefore, they should not be used without additives, in order to ensure the integrity of the circuit against corrosion.
The following are the results of tests evaluating the corrosion of various metals, conducted in accordance with the ASTM D 1384 standard. The results shown are from the study carried out by INTA.
| Material | Blue Sun® −28 °C | ASTM D 3306 max. |
|---|---|---|
| Copper | 0.5 | 10 |
| Solder | 0.1 | 30 |
| Brass | −0.5 | 10 |
| Mild steel | −0.9 | 10 |
| Cast iron | −3.7 | 10 |
| Aluminium | 2.0 | 30 |
The results above represent the average change in the weight of the test specimens, in mg. A negative value indicates a weight increase due to the formation of a stable protective layer on the metal surface.
The following table shows the results of tests performed in accordance with ASTM D 4340:
| Material | Product | Result | Max. |
|---|---|---|---|
| Aluminum | Blue Sun® 25 % V/V | 0.5 mg/cm²·week | 1.0 mg/cm²·week |
Description of the ASTM D 1384 test: in this test method, metal specimens typical of those found in engine cooling systems are totally immersed in aerated solutions of engine coolant and corrosive water for 336 hours at 88 °C. The corrosion-inhibiting properties of the test solution are evaluated based on the weight changes undergone by the specimens. Each test is performed in triplicate, and the average weight change for each metal is determined.
Description of the ASTM D 4340 test: in this test method, a heat flux is established through a cast aluminum alloy of the type typically used for engine cylinder heads while it is exposed to an engine coolant at a pressure of 193 kPa (28 psi). The temperature of the aluminum specimen is maintained at 135 °C, and the test is conducted for one week (168 h). The effectiveness of the coolant in preventing aluminum corrosion under heat-transfer conditions is evaluated based on the change in weight of the test specimen.
Compatible materials
Blue Sun® −28 °C is compatible with materials commonly used in thermal circuits. The following table shows the plastics, sealants, and elastomers compatible with mixtures of the product and water at standard ratios. The data comes from a specific bibliography and from the trials themselves.
| Name | Abbreviation |
|---|---|
| Butyl rubber | IIR |
| Chloroprene | CR |
| Ethylene-propylene-diene rubber | EPDM |
| Fluorocarbon elastomers | FPM |
| Natural rubber (up to 80 °C) | NR |
| Nitrile rubber | NBR |
| Polyoxymethylene | POM |
| Polyamide (up to 115 °C) | PA |
| Polybutene | PB |
| Polyethylene high/low density | PE-LD / PE-HD |
| Polyethylene cross linked | VPE |
| Polypropylene | PP |
| Poly(tetrafluoroethylene) | PTFE |
| Polyvinyl chloride, rigid | PVC h |
| Silicone | Si |
| Styrene-butadiene rubber (up to 100 °C) | SBR |
| Unsaturated polyester resins | UP |
Phenolic resins, plasticized PVC, and polyurethanes are not compatible with Blue Sun® −28 °C.
Propylene glycol and its dilutions are incompatible with zinc, as they dissolve it. Avoid containers that contain zinc.
If the system contains galvanized pipes, a whitish solid substance will appear when operation begins. Once this is removed, the underlying carbon steel remains protected by Blue Sun® −28 °C, and no further precautionary measures are required.
Thermophysical tables
Blue Sun® −28 °C thermodynamic properties as a function of temperature.
Blue Sun® −28 °C
| Temperature °C |
Density kg/m³ |
Heat capacity kJ/kg·K |
Thermal conductivity W/m·K |
Dynamic viscosity mPa·s |
Kinematic viscosity mm²/s |
Prandtl number | Coefficient of thermal expansion ·10⁻⁵ 1/K |
Vapor pressure mbar |
|---|---|---|---|---|---|---|---|---|
| −28 | 1,056.2 | 3.654 | 0.406 | 76.60 | 72.53 | 689.43 | 11.0 | 0 |
| −20 | 1,054.7 | 3.669 | 0.409 | 40.65 | 38.54 | 365.54 | 23.8 | 0 |
| −10 | 1,051.5 | 3.689 | 0.413 | 20.35 | 19.35 | 182.69 | 36.7 | 0 |
| −5 | 1,049.4 | 3.698 | 0.415 | 14.93 | 14.23 | 133.92 | 42.0 | 0 |
| 0 | 1,056.9 | 3.708 | 0.417 | 11.19 | 10.69 | 100.32 | 46.7 | 0 |
| 10 | 1,041.8 | 3.728 | 0.421 | 6.67 | 6.40 | 59.67 | 54.6 | 0 |
| 20 | 1,035.8 | 3.747 | 0.425 | 4.26 | 4.11 | 37.99 | 60.7 | 0 |
| 30 | 1,029.3 | 3.766 | 0.429 | 2.88 | 2.80 | 25.63 | 65.4 | 0 |
| 40 | 1,022.4 | 3.784 | 0.432 | 2.05 | 2.00 | 18.18 | 69.1 | 13 |
| 50 | 1,015.2 | 3.802 | 0.436 | 1.52 | 1.50 | 13.46 | 71.8 | 108 |
| 60 | 1,007.8 | 3.820 | 0.439 | 1.17 | 1.16 | 10.34 | 73.9 | 198 |
| 70 | 1,000.2 | 3.837 | 0.442 | 0.93 | 0.93 | 8.21 | 75.4 | 305 |
| 80 | 992.6 | 3.854 | 0.445 | 0.76 | 0.77 | 6.71 | 76.4 | 452 |
| 90 | 985.0 | 3.870 | 0.448 | 0.64 | 0.65 | 5.61 | 77.0 | 661 |
| 100 | 977.4 | 3.885 | 0.451 | 0.55 | 0.56 | 4.80 | 77.3 | 957 |
Directions for use
Before filling, the circuit must be flushed with water to remove scale and assembly debris, as well as flux residues—especially when fluxes containing chloride, fluoride, or borax have been used.
After the pressure test—during which the exact volume of the circuit can also be determined using a meter—the system must be filled with a mixture of antifreeze and water (or pure antifreeze) and the fluids mixed within the circuit via recirculation. It is not advisable to leave the circuit empty after the pressure test, particularly if carbon steel is present, as it is highly susceptible to damage.
It is recommended to properly bleed the circuit after start-up to eliminate any potential air pockets.
For a circuit already in use, after draining the previous antifreeze, the system must be flushed with water to remove sediment and particles before filling it with Blue Sun® −28 °C. Pre-existing corrosion can significantly shorten the product’s service life. If corrosion is detected, corrective measures must be taken before filling the system. Depending on the condition of the previous fluid, it is recommended to clean the circuit before filling—for example, using CS-LTV or Luzar® LD.
It is recommended to use Teflon tape or hemp to seal threaded joints. Check the compatibility of other products with propylene glycol before use.
The product is ready to use; do not dilute or mix with other products.
Mixing with other types of antifreeze should be avoided due to potential incompatibilities that could reduce the product’s service life. For information on specific compatibilities, please contact our technical department at carpemar@carpemar.com.
The lower surface tension of Blue Sun® −28 °C compared to water can make minor damage caused by previous corrosion more apparent.
Operating temperature
Sustained temperatures above 180 °C cause premature aging of the propylene glycol. Therefore, for solar thermal installations with stagnation temperatures exceeding 180 °C, it is recommended to select expansion vessels of sufficient size to ensure that the solar antifreeze fluid is fully accommodated in the event of stagnation.
Temperatures above 200 °C cause a slow alteration of the chemical properties of the antifreeze liquid, which can jeopardize the operational reliability of the system.
In the case of non-closed systems or the introduction of oxygen (for example, via valves), the maximum operating temperature is lower.
Maintenance – Service life
The service life of Blue Sun® −28 °C is at least five years in a closed circuit operating between the freezing point and 100 °C. Practical experience shows that the fluid does not degrade under the operating conditions described in this section, resulting in a longer service life.
To verify the product’s performance, the most important parameters are measurements of pH and glycol concentration. Generally, this monitoring procedure can be carried out once a year or every two years.
The glycol content must not differ from the initial value. The appropriate pH range is between 7.5 and 9.0. Outside this range, the product must be analyzed to determine the cause and the procedure to follow.
Dosage
Precautions
Blue Sun® −28 °C is a non-flammable and non-corrosive product, so it does not require special precautions. In any case, good industrial practices are recommended.
Avoid contact with eyes. In case of contact, rinse the eye with plenty of water for 10 minutes. Do not ingest and keep out of reach of children.
When stored in its original, tightly sealed containers at temperatures between 5 and 35 °C and away from direct sunlight, the product retains its properties for at least 24 months.
Downloadable documents
Find all the relevant documentation about the product: technical data sheets and safety data sheets.
